Apparatus for supporting a structure for motion in response to fluid response to fluid pressure



March 9, 1965 P. M. MAXWELL 3,173,007

APPARATUS FOR SUPPORTING A STRUCTURE FOR MOTION IN RESPONSE TO F LUI-D PRESSURE Filed July 26, 1962 INVENTOR FIG'Z PALMER M. MAXWELL BY wg/m/ ATTORNEY United States Patent APPARATUS FOR SUPPORTING A STRUC- TURE FOR MOTION IN RESPONSE TO FLUID PRESSURE Paimer M. Maxwell, 5 Wymberly Point Drive,

Savannah, Ga. Filed July 26, 1962, Ser. No. 212,573 6 Claims. (til. 250-63) This invention relates to apparatus for imparting reciprocating motion to a structure, and more particularly to means for mounting a Bucky diaphragm grid used in X-ray radiography so that continuous motion of the Bucky diaphragm grid may be obtained without mechanical friction, vibration or noise and may be directly responsive to a source of external pressure changes.

It is the function of the Bucky diaphragm grids used in radiography to screen from the X-ray film those secondary radiations which would blur the radiographic image if they were unobstructed. Since the parallel interspaced lead strips of these Bucky diaphragm grids are themselves opaque to X-ray, they would cast their shadows on the film if the Bucky grid were stationary during X-ray exposure. To obliterate such shadows, it is well established practice to continuously reciprocate Bucky diaphragm grids with reference to the stationary surface of the photographic medium just prior to and during X-ray exposure.

Various types of apparatus have been used to impart continuous reciprocating motion to Bucky grids and to I support such Bucky grids so that reciprocating motion is possible. Without exception, these previous types of apparatus have supported the Bucky grid by arrangements such as hearing blocks fixedly associated with the Bucky grid carriage and slidably resting on stationary rods. Slidable motion of the Bucky grid carriage and bearing blocks with reference to the rods is accomplished by direct mechanical attachment of the electro-mechanical or other reciprocating means to some point on the Bucky grid carriage.

Regardless of the specific previous arrangement used, the result has been mechanical friction, vibration and noise' as the Bucky grid carriage moved in a rapid reciprocating manner. The mechanical friction not only may cause binding or jamming of the apparatus but, it also produces objectionable vibration and noise and is a possible source of heat or sparking which could be hazardous in a potentially explosive environment such as an operating room.

Moreover, the use of various devices such as an electro-mechanical reciprocating means directly connected to the Bucky grid carriage to obtain reciprocating motion introduces additional difficulties. This is because their motion is another possible source of mechanically induced heat or sparks and because the association of various switches with them and in other areas adjacent to the Bucky diaphragm in order to control Bucky grid motion is a source of electrically induced hazards, intolerable for safe use in an explosion sensitive area such as an operating room.

In addition, the nature of devices such as electromechanical assemblies for imparting motion to mechanically supported diaphragms is such that the force is almost always applied to the Bucky grid carriage in an asymmetrical manner. This increases the possibility of jamming and the hazards of mechanical friction as the Bucky grid carriage slides on its mechanical support.

The invention disclosed herein eliminates all of the foregoing difiiculties associated with previously existing means for imparting motion to Bucky grids. This is achieved by supporting the Bucky grid between two exice pandable-collapsible means so that the expansion of one means and collapse of the other means will move the Bucky grid. The Bucky grid is attached directly to the two expandable-collapsible means and is supported entirely by them. There is no mechanical vibration or noise as the Bucky grid moves rapidly back and forth in a reciprocating motion.

Moreover, the expandable-collapsible means are placed at each side of the Bucky grid so that the centerline of expansion and collapse of each coincides with that of the other and with the centerline of Bucky grid motion. Thus, both the magnitude and direction of Bucky grid motion is fixed and controlled by the motion of the two expandable-collapsible means. This not only permits any desired degree of Bucky grid motion but the symmetrical application of force to the Bucky grid insures that it will not scrape or bind against adjacent structures.

Any source of two equal, but opposite, fluid pres sures capable of being continuously reversed a plurality of times is suitable for use with the two expandablecollapsible means. Such a source of fluid pressure may be located remote from the Bucky diaphragm assembly since a duct or tube leading from the source to each of the expandable-collapsible means is the only type of association required between the pressure source and the area of the Bucky diaphragm assembly. Motion of the Bucky grid is directly dependent upon continuously reversing pressures transmitted to the two expandablecollapsible means and all switches and other apparatus for controlling Bucky grid motion may be associated with the remotely placed pressure source. Not only does the invention avoid the mechanical and electrical hazards normally associated with the sources of the force or pres sure necessary to move a Bucky grid or with the mechanisms to control motion, but it permits the structure in the area of actual Bucky grid use to be very compact.

These and other features of the invention will be more clearly understood from the following detailed description and the accompanying drawings in which like characters designate corresponding parts in all figures and in which:

FIGURE 1 is a sectional view taken along the centerline of Bucky grid motion and shows the Bucky diaphragm housing, a support block with resilient face at each side of the Bucky grid, a tongue bonded to each resilient face and extending into the cavity of the support block, a bracket bar integrally associated with each tongue, and a Bucky grid extending between the two bracket bars.

FIGURE 2 is a sectional view taken in line 2-2 in FIGURE 1 and shows the Bucky diaphragm housing and tongue in section, and the dashed outline of the innermost edge of a support block to which a resilient face has been bonded.

FIGURE 3 is a side elevation view of a pressure source suitable for increasing and decreasing the fluid in the support blocks so as to move the resilient face of each, and with a portion of each cylinder cut away to show the position of the piston in each cylinder.

These figures and the following detailed description disclose a preferred specific embodiment of the invention, but the invention is not limited to the details disclosed since it may be embodied in other equivalent forms.

The specific embodiment of the invention described herein is most easily understood by considering the Bucky grid 10 to be mounted within a box-like Bucky diaphragm constantly reciprocating Bucky grid 16, and out the bottom aperture 13 to the photographic medium. Thus, the Bucky grid is able to accomplish its purpose of screening the photographic medium from secondary radiation.

Within two opposite sides of the Bucky diaphragm housing 11 are positioned support blocks 14 and 15. These support blocks'l i and 15 are identical in that each is arigid block-like structure having an elliptical cavity 16 inone surface. In the specific embodiment described herein-each support block 14 M15 is also elliptical in cross-section and the cavity is in'one of the elliptical surfaces. Thus, an elliptical edge or lip 17 is formed by the cavity 16/ It is to thiselliptical edge or'lip 17 that a resilient face 18 is attached by bonding or other suitable means to forma chamber 19' boundedby the surface of the cavity 16 and the inner surface 20 of the resilient face 18.

The support blocks 14 and 15 are positioned within the Bucky diaphragm housing 11 so that the resilient face 18 associated with one is opposite that of the other and so that a line extending through the center of each resilient face 18 will coincide with the centerline of the Bucky grid along which motion is desired. The support blocks 14 and 15 are held in these positions by screws 21 extending through the Bucky diaphragm housing 11 and into each support block 14 or 15.

To the resilient face 18 of each support block 14 or 15 is attacheda' tongue 22. At one end 23, the outside contour of each tongue '22 resembles the contour of the cavity 16 in a support block 14 or 15. However, the size of this end 23 of the tongue 22 is sutficiently less than the size of the cavity 16 to permit the tongue 22 to enter the cavity 16 with a resilient face 18 between the tongue 22 and surface'of the cavity 16.

At its other end 24, each tongue 22 is fixedly associated with a bracket bar 25. It is to the bracket bar 25 that the Bucky grid is attachedby inserting one edge into a slot 26. Each slot 26 is of sufiicient length to firmly hold one side or edge 27 of the Bucky grid 10 to which it is fixedly attached by an attachment screw 28.

From the foregoing, it is readily apparent that the positioning of the Bucky grid 10 within the Bucky diaphragm housing 11 is achieved by attaching bracket bars 25 to opposite sides 27 of the Bucky grid 10, by attaching tongues 22 to bracket bars 25, and by positioning the tongues 22 in the cavities 16 of the support blocks 14 and 15. In short, since the ends 23 of the tongues 22 are bonded or otherwise attached to the resilient faces 18 associated with the support blocks 14 and 15, the Bucky grid 10 is supported between two resilient faces 18 positioned at opposite ends of the Bucky grid 16 with their centers in the centerline of the Bucky grid 10 along which Bucky grid 10 motion is desired.

The distance between support blocks 14 and is such that when the Bucky grid 10 is supported between two resilient faces 18, the tongues 22 will force the resilient face 18 associated with each support block 14 or 15 into the cavity 16 of the support block 14 or 15. Thus, when supporting the Bucky grid 10, each resilient face 18 has a concave shape resembling that of the cavity 16 with which it is associated.

It is readily apparent that when one resilient face 18 is made less concave and the other resilient face 18 is made more concave, the Bucky grid 10 will move toward that resilient face 18 which is made more concave. It is in this manner that motion is imparted to the Bucky grid 10.

The required motion or change in shape of the resilient faces is achieved by changing the volume of fluid in chambers 19 of support blocks 14 and 15. When the fluid in one chamber 19 is increased and that in the other is decreased by a corresponding amount the resulting motion of the resilient faces 18 will move the Bucky grid 10 toward support block 14 or 15. Reversing the fluid volume changes will result in Bucky grid 10 motion in the opposite direction and it is obvious that frequent approif, priate and continuous changes in the volume of fluid in the support blocks 14 and 15 will result in continuous reciprocating motion of the Bucky grid 10 which is directly related in frequency and magnitude to the frequency an magnitude of the fluid volume changes. The required changes in the volume of fluid in the support blocks 14- and 15 is achieved by simultaneously increasing and decreasing the fluid in the chambers 19 by an equal amount through two ducts 29, each leading to one of the chambers 19 from a source of fluid pressure. In the specific embodiment of the invention described herein, this source of fluid pressure-is comprised of two cylinders 39, each having a movable piston 31.within. The pistons 31 are attached by piston rods to a common crank shaft. One cylinder 39 is connected by duct 29 to the chamber 19 of support block 14 and the othercylinder 3t? is connected by another duct 29 to the chamber 19 of support block 15.

A suitable motor 32 attached to the external portion of the crank shaft is used to move the pistons 31 in the cylinders 30 so as to decrease the fluid volume in one cylinder 31) while simultaneously increasing it in the other cylinder 311. This assures a complete pressure reversal within cylinders 3% each revolution of the motor 32. Since each cylinder 36') is connected directly to a chamber 19 of a support block 14 or 15 by a duct 29, this motion of pistons 31 will cause the volume of fluid in each chamber 19 to increase or decrease in the manner described above so that continuous reciprocating motion of the Bucky grid 10 is'obtained.

The'inotion of the Bucky grid-1d is directly related to the output of the fluid pressure source. Therefore, all control switches and other mechanisms for controlling Bucky grid 10 reciprocating motion may be located at a source of fluid pressure which may be remote from-Bucky Motion of the Bucky grid in a constant horizontal plane is maintained by selecting a material for the iresilient faces 18 which has sufficient resiliency to resist any tendency of the weight of the Buckygrid 10'to pull the areas of the resilient faces 18 to which the tongues 22 are attached out of a fixed horizontal plane. If the trnater-ial used for the resilient faces 18 possesses this degree of resliency regardless of the extent to which a resilient face 18 is concave, it is apparent that the ends 23 of the tongues 22 and the Bucky diaphragm 10 will not shift in vertical position as the Bucky grid 10 is moved by making the resilient faces 18 more or less concave.

What is claimed as invention is:

1. A device for supporting and moving an X-ray Bucky diaphragm grid comprising, in combination, two expandable-collapsible means, one attached to one side of the grid, the other attached to the opposite side of the grid, and both means being expandable and collapsible along a line extending between them and having resistance to defonmation transverse to said line which is sufficient to maintain the grid in a single plane of motion; means for expanding one expandable-collapsible means while simultaneously collapsing the other expandable-collapsible means an equal amount, said means being continuously reversible so as to impart a continuous reciprocating motion to the grid.

2. Apparatus for supporting and imparting motion to a Bucky diaphragm grid comprising, in combination, two concave resilient faces, the first having its concave surface fixedly joined to a side of said grid, the second having its concave surface fixedly joined to the side of said grid opposite to that to which the first resilient face is joined, both being resiliently movable by varying the concavity of said surfaces along a line of motion coinciding'with the centerline of the grid extending between the two sides of the grid to which they are joined, and both having sufiicient resistance to deformation in a direction perpendicular to said line of motion to resist such deformation by forces whose total is equal to the force exerted by the weight of the grid, and means for simultaneously moving both resilient faces in the same direction along the line of motion along which they are movable.

3. Apparatus for supporting and imparting reciprocating motion to an X-ray Bucky diaphragm grid comprising, in combination, two support blocks, the first support block being fixedly positioned adjacent to a side of the said grid and having a cavity in that surface nearest to said grid and the second support block being fixedly positioned adjacent to the side of said grid opposite that to which the first support block is adjacent and having a cavity in that surface nearest to said grid; two resilient faces, the first resilient face being fixedly positi-oned across the cavity in the first support block so as to form a resilient side to a first chamber bounded by it and said cavity and the second resilient face being fixedly positioned across the cavity in the second so port block so as to form a resilient side to a second chamber bounded by it and said cavity; two attachment means, the first attachment means being attached to and extending between the side of the grid adjacent to the first support block and the resilient face positioned across the cavity in the first support block, the second attachment means being attached to and extending between the side of the grid adjacent to the second support block and the resilient face positioned across the cavity in the second support block, and each being of sufficient length so that its extending length when added to that of the other and of the grid between them will equal a total distance which is greater than the distance between the surfaces of the support blocks adjacent to the grid; two fiuids, one completely filling the first chamber and the other completely filling the second chamber; and means for increasing the amount of fluid in the first chamber while simultaneously decreasing the amount of fluid in the second chamber an equal amount, said means having sufiicient fluid pressure to move the resilient face of the first support block toward the second support block.

4. Apparatus for supporting and imparting reciprocating motion to an X-ray Bucky diaphragm grid comprising, in combination, two support blocks, the first support block being fixedly positioned adjacent to a side of the said grid and having a cavity in that surface nearest to said grid and the second support block being fixedly positioned adjacent to the side of said grid opposite that to which the first support block is adjacent and having a cavity in that surface nearest to said grid; two resilient faces, the first resilient face being fixedly positioned across the cavity in the first support block so as to form a resilient side to a first chamber bounded by it and said cavity and the second resilient face being fixedly positioned across the cavity in the second support block so as to form a resilient side to a second chamber bounded by it and said cavity; two attachment means, the first attachment means being attached to and extending between the side of the grid adjacent to the first support block and the resilient face positioned across the cavity in the first support block, the second attachment means being attached to and extending between the side of the grid adjacent to the second support block and the resilient face positioned across the cavity in the second support block, and each being of sufiicient length so that its extending length when added to that of the other and of the grid between them will equal a total distance which is greater than the distance between the surfaces of the support blocks adjacent to the grid; two hydraulic cylinders, each having a piston positioned within; a crank shaft; two piston rods, the first attached at its ends to the piston in one cylinder and the crank shaft and the second attached at its ends to the piston in the other cylinder and the crank shaft and having its point of attachment to the crank shaft from the point of attachment of the first; two tubes, the first tube extending from the interior of one cylinder to the interior of the first chamber and the second tube extending from the interior of the other cylinder to the interior of the second chamber; fluid filling both chambers, tubes, and cylinders; motor means for rotating the crank shaft; means for simultaneously starting the motor means and X-ray tube rotation; and means for initiating X-ray exposure subsequent to the start of the motor means and X-ray tube rotation.

5. Apparatus for supporting and imparting reciprocating motion to a structure comprising, incombination, two support blocks, the first support block being fixedly positioned adjacent to a side of the said structure and having a cavity in that surface nearest to said structure and the second support block being fixedly positioned adjacent to the side of said structure opposite that to which the first support block is adjacent and having a cavity in that surface nearest to said structure; two resilient faces, the first resilient face being fixedly positioned across the cavity in the first support block so as to form a resilient side to :a first chamber bounded by it and said cavity and the second resilient face being fixedly positioned across the cavity in the second support block so as to form a resilient side to a second chamber bounded by it and said cavity; two attachmerit means, the first attachment means being attached to and extending between the side of the structure adjacent to the first support block and the resilient face positioncd across the cavity in the first support block, the second attachment means being attached to and extending between the side of the structure adjacent to the second support block and the resilient face positioned across the cavity in the second support block, and each being of sufiicient length so that its extending length when added to that of the other and of the structure between them will equal a total distance which is greater than the distance between the surfaces of the support blocks adjacent to the structure; two fluids, one completely filling the first chamber and the other completely filling the second chamber; and means for increasing the amount of fluid in the first chamber while simultaneously decreasing the amount of fluid in the second chamber an equal amount, said means having sufiicient fluid pressure to move the resilient face of the first support block toward the second support block.

6. Apparatus for supporting and imparting recipro eating motion to a structure comprising, in combination, two support blocks, the first support block being fixedly positioned adjacent to a side of the said structure and having a cavity in that surface nearest to said structure and the second support block being fixedly positioned adjacent to the side of said structure opposite that to which the first support block is adjacent and having a cavity in that surface nearest to said structure; two resilient faces, the first resilient face being fixedly positioned across the cavity in the first support block so as to form a [resilient side to a first chamber bounded by it and said cavity and the second resilient face being fixedly positioned across the cavity in the second support block so as to form a resilient side to a second chamber bounded by it and said cavity; two attachment means, the first attachment means being attached to and extending between the side of the structure adjacent to the first support block and the resilient face positioned across the cavity in the first support block, the second attachment means being attached to and extending between the side of the structure adjacent to the second support block and the resilient face positioned across the cavity in the second support block, and each being of sufficient length so that its extending length when added to that of the other and of the structure between them will equal a total distance which is greater than 7 the distance between the surfaces of the support blocks adjacentto the structure; two hydraulic cylinders, each having apiston positioned Within; a crank shaft; two piston rods, the first attached at its ends to the piston in one cylinder and the crank shaft and-the second attached et its ends to the piston in the other cylinder vand the crank shaft and having its point of attachment to the crank shaft 180 from the point of attachment of the first; two tubes, the first tube extending from the interior of onecylinder to the-interior of the first chamber and thev second tube extending from the interior of the other cylinder to the interior of the second cham- 0 her; fluid til-ling both chambers, tubes, and cylinders; and motor means for rotating the crank shaft.

References Cited by the Examiner UNITED STATES PATENTS RALPHG. NILSON, Primary Exqminer. 

1. A DEVICE FOR SUPPORTING AND MOVING AN X-RAY BUCKY DIAPHRAGM GRID COMPRISING, IN COMBINATION, TWO EXPANDABLE-COLLAPSIBLE MEANS, ONE ATTACHED TO ONE SIDE OF THE GRID, THE OTHER ATTACHED TO THE OPPOSITE SIDE OF THE GRID, AND BOTH MEANS BEING EXPANDABLE AND COLLAPSIBLE ALONG A LINE EXTENDING BETWEEN THEM AND HAVING RESISTANCE TO DEFORMATION TRANSVERSE TO SAID LINE WHICH IS SUFFICIENT TO MAINTAIN THE GRID IN A SINGLE PLANE OF MOTION; MEANS FOR EXPANDING ONE EXPANDABLE-COLLAPSIBLE MEANS WHILE SIMULTANEOUSLY COLLAPSING THE OTHER EXPANDABLE-COLLAPSIBLE MEANS AN EQUAL AMOUNT, SAID MEANS BEING CONTINUOUSLY REVERSIBLE SO AS TO IMPART A CONTINUOSU RECIPROCATING MOTION TO THE GRID. 